Conservative fans of Mad Men are shouting liberal bias after the AMC show took potshots at Charlton Heston and at Mitt Romney’s dad, George Romney, who was governor of Michigan in 1966 when Sunday’s episode was set. On Monday, the governor’s grandson tweeted his response to the episode.

“Seriously, lib media mocking my dead grandpa?” tweetedTagg Romney, the eldest son of Mitt, who is the frontrunner for the Republican nomination for president.

"George Romney was as good a man I’ve ever known. Inspirational leader, worked for civil rights, promoted freedom. We need more like him,” Tagg said in a follow-up tweet.

In other words, not exactly the “clown” that Mad Men character Henry Francis thinks he is.

In the episode, a clip of which is below, Francis is on the phone presumably explaining why his boss, New York Mayor John Lindsay, doesn’t want to appear in Michigan alongside its governor. “Because Romney’s a clown, and I don’t want him standing next to him,” Francis says.

In a third tweet on the subject, Tagg Romney wrote: "Dad is fair game, grandpa isn't."

The same episode also took a dig at another dead member of the GOP: Heston, the Oscar-winning star of Ben Hur and former NRA president, though in 1966 Heston was a Democrat who supported more restrictive gun-control laws. Apparently he was also into smoking great weed, according to Mad Men character Harry Crane.

Heston died in 2008. A spokeswoman for his son, Fraser Heston, said he doesn’t watch the show and therefore he had no comment on Sunday’s episode.

John Nolte at Breitbart.com was one of the first conservative commentators to weigh in on the episode, writing that it “seems odd that such an outstanding show would throw a spell-breaking sucker punch at George Romney (and by extension our probable nominee).”

"Republican fans of the show,” Nolte wrote, “will now have to worry about more of this straight through to the end of the season. The left will say what they always say when they read posts like this: ‘oh, relax, take a joke’ (because they're so good at doing both) -- which is easy to say when this never happens to you. And we can relax and take a joke, and we are quite used to falling out of love with television shows that turn on us.”

“Mad Men may not be jumping the (shark) quite yet,” wrote Freddy Gray at U.K.'s The Spectator after Sunday’s episode, but the series “is showing signs of collapsing under the weight of its own hype. The carefully built ambiguity of the first few seasons is being lost, replaced by cheesy self-awareness and standard-issue liberal correctness.”

After explaining the scene attacking George Romney, Gray writes: “The line is also a dig at Mitt, who will in all likelihood oppose President Obama in this year’s election. We can hazard a guess as to which politician the people who bring us Mad Men will be supporting.”